[Glucocorticoid and Bone. Significance of serum soluble RANKL measurement in patients under glucocorticoid therapy].

Receptor activator of nuclear factor-κB ligand (RANKL) stimulates osteoclast differentiation and activation via binding to its receptor RANK on the pre-osteoclast cells. RANKL is a transmembrane protein, but soluble form (soluble RANKL ; sRANKL) is also circulating in the blood. The origins of the sRANKL have been thought to be produced by cleavage of membrane RANKL or secreted by T-lymphocytes, however, it is recently reported that osteocytes were one of the major sources of sRANKL. However, the pathophysiological roles of serum sRANKL has not been clarified yet. We prospectively measured serum sRANKL and OPG levels before and after the initiation of glucocorticoid therapy in patients with systemic autoimmune diseases. It was suggested that serum sRANKL might be a useful marker of bone remodeling in these patients under glucocorticoid therapy. This paper reviewed significance of sRANKL measurement in various bone metabolic diseases including glucocorticoid-induced osteoporosis.